Mitochondrial ferritin deficiency reduces male fertility in mice.

Mitochondrial ferritin (FtMt) is a functional ferritin targeted to mitochondria that is highly expressed in the testis. To investigate the role of FtMt in the testis we set up a series of controlled matings between FtMt gene-deletion mice (FtMt-/-) with FtMt+/+ mice. We found that the number of newborns per litter and the fertility rate were strongly reduced for the FtMt-/- males, but not for the females, indicating that FtMt has an important role for male fertility. The morphology of the testis and of the spermatozoa of FtMt-/- mice was normal and we did not detect alterations in sperm parameters or in oxidative stress indices. In contrast, we observed that the cauda epididymides of FtMt-/- mice were significantly lighter and contained a lower number of spermatozoa compared with the controls. Also, the ATP content of FtMt-/- spermatozoa was found to be lower than that of FtMt+/+ spermatozoa. These data show that FtMt contributes to sperm epididymis maturation and to male fertility.